U.S. Pat. No. 5,198,111 (attorney's reference RP Case 19), assigned to the Assignee of the present invention, discloses an industrial pressure filter system having a cylindrical filter element, an unfiltered liquid inlet communicating with the interior of the filter element and a filtered liquid outlet communicating with the outside of the filter element. A screw extends axially within the filter element and is rotatable in opposite directions to axially move a cleaning member in opposite axial directions therealong within the filter element for cleaning the inlet side of the filter element. Holes in the cleaning member allow axially flow of liquid to be filtered therethrough, so that liquid to be filtered can always reach substantially the entire length of the filter element. Threadless portions at the end of the screw allow the cleaning member to idle thereon while awaiting a reversal of screw rotation direction. Springs cooperate with the threadless portions to axially urge the cleaning member onto the threaded portion of the screw upon reversal of screw rotation direction to carry the cleaning member back in the opposite direction along the length of the screw. The cleaning member includes a radially thin, radially bendable circular wiper element backed radially by a backing O-ring resiliently compressed diametrally in its cross section for urging the circular wiper element resiliently out against the interior wall of the filter element.
While this prior system has worked well and been commercially successful, a continuing effort to improve thereon has resulted in the present invention.
The objects and purposes of the present invention include providing an improved self-cleaning filter system of the type above generally described. Further objects and purposes of the invention will be apparent to persons acquainted with apparatus of this general kind upon reading the following description and inspecting the accompanying drawings.